<template>
  <div class="breadcrumb-container">
    <div class="breadcrumb-decoration"></div>
    
    <el-breadcrumb class="app-breadcrumb" separator="/">
      <transition-group name="breadcrumb">
        <el-breadcrumb-item v-for="(item, index) in levelList" :key="item.path">
          <span 
            v-if="item.redirect === 'noRedirect' || index == levelList.length - 1" 
            class="no-redirect"
          >
            {{ item.meta.title }}
          </span>
          <a v-else @click.prevent="handleLink(item)" class="redirect-link">
            {{ item.meta.title }}
          </a>
        </el-breadcrumb-item>
      </transition-group>
    </el-breadcrumb>
  </div>
</template>

<script>
export default {
  data() {
    return {
      levelList: null
    }
  },
  watch: {
    $route(route) {
      // if you go to the redirect page, do not update the breadcrumbs
      if (route.path.startsWith('/redirect/')) {
        return
      }
      this.getBreadcrumb()
    }
  },
  created() {
    this.getBreadcrumb()
  },
  methods: {
    getBreadcrumb() {
      // only show routes with meta.title
      let matched = []
      const router = this.$route
      const pathNum = this.findPathNum(router.path)
      // multi-level menu
      if (pathNum > 2) {
        const reg = /\/\w+/gi
        const pathList = router.path.match(reg).map((item, index) => {
          if (index !== 0) item = item.slice(1)
          return item
        })
        this.getMatched(pathList, this.$store.getters.defaultRoutes, matched)
      } else {
        matched = router.matched.filter(item => item.meta && item.meta.title)
      }
      // 判断是否为首页
      if (!this.isDashboard(matched[0])) {
        matched = [{ path: "/index", meta: { title: "首页" } }].concat(matched)
      }
      this.levelList = matched.filter(item => item.meta && item.meta.title && item.meta.breadcrumb !== false)
    },
    findPathNum(str, char = "/") {
      let index = str.indexOf(char)
      let num = 0
      while (index !== -1) {
        num++
        index = str.indexOf(char, index + 1)
      }
      return num
    },
    getMatched(pathList, routeList, matched) {
      let data = routeList.find(item => item.path == pathList[0] || (item.name += '').toLowerCase() == pathList[0])
      if (data) {
        matched.push(data)
        if (data.children && pathList.length) {
          pathList.shift()
          this.getMatched(pathList, data.children, matched)
        }
      }
    },
    isDashboard(route) {
      const name = route && route.name
      if (!name) {
        return false
      }
      return name.trim() === 'Index'
    },
    handleLink(item) {
      const { redirect, path } = item
      if (redirect) {
        this.$router.push(redirect)
        return
      }
      this.$router.push(path)
    }
  }
}
</script>

<style lang="scss" scoped>
.breadcrumb-container {
  position: relative;
  padding: 8px 16px;
  background-color: transparent;
  
  .breadcrumb-decoration {
    position: absolute;
    bottom: 0;
    left: 16px;
    height: 2px;
    width: 24px;
    background: linear-gradient(to right, #8ba1bc, #6b7e97);
    border-radius: 2px;
    opacity: 0.7;
  }
}

.app-breadcrumb.el-breadcrumb {
  display: inline-block;
  font-size: 14px;
  line-height: 32px;
  
  .redirect-link {
    color: #6b7e97;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s;
    position: relative;
    
    &::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: -2px;
      width: 100%;
      height: 1px;
      background-color: #8ba1bc;
      transform: scaleX(0);
      transition: transform 0.3s ease;
      transform-origin: bottom right;
    }
    
    &:hover {
      color: #4a5568;
      
      &::after {
        transform: scaleX(1);
        transform-origin: bottom left;
      }
    }
  }
  
  .no-redirect {
    color: #a0aec0;
    cursor: text;
    font-weight: 400;
  }
  
  .el-breadcrumb__separator {
    margin: 0 8px;
    color: #cbd5e0;
  }
  
  .el-breadcrumb__item:last-child .el-breadcrumb__inner {
    color: #4a5568;
    font-weight: 600;
  }
}

// 面包屑动画
.breadcrumb-enter-active,
.breadcrumb-leave-active {
  transition: all .5s;
}

.breadcrumb-enter,
.breadcrumb-leave-active {
  opacity: 0;
  transform: translateX(20px);
}

.breadcrumb-move {
  transition: all .5s;
}

.breadcrumb-leave-active {
  position: absolute;
}
</style>
